Phenomena Accompanying Transmission with Some Types of Star Transformer Connections-II

1. Hysteresis, as well as variation of permeability, gives rise to harmonics of considerable magnitude in the exciting current of a transformer; the components from the two sources are in quadrature for each harmonic. 2. There is a fallacy in the idea that the harmonics in the exciting current of a transformer are entirely wattless. 3. For transmission lines of modern lengths, the effect of the line is to reduce the third harmonic voltage between neutral and line terminals of a star-star connected bank of transformers having grounded neutral on the line side only. 4. In transmission with star-star transformer banks having grounded neutral on the line side only, the inter-relation of line susceptance from conductor to ground in series with the varying susceptance of the individual transformers may cause the total m. m. f. of one of the transformers to pass through zero at the same instant as the impressed e. m. f.; and thus, give opportunity for a reversal of this transformer due to inertia, thereby producing a periodically reversing leg and abnormal voltages. 5. In a similar system with high quality line insulation, the effect of atmospheric charges on the line conductors may be to cause the transformers of the bank to assume relations with one leg permanently reversed when energized from the station side; thus, imposing unbalanced voltage conditions on the bank and producing, in two of the units, fundamental frequency components of voltage 264 per cent of normal. 6.